Is a vpn recommended for my iPad while travelling

You will likely receive conflicting advice concerning the use of VPNs.

Insofar as public WiFi hotspots are concerned, where your internet traffic can be both monitored and potentially manipulated by bad/malicious actors, use of a properly configured reputable VPN service is certainly recommended by knowledgable Infosec Professionals.

Public networks have a considerably higher risk profile than private networks - the latter, by design, being considerably more secure. Unknown to many, while some of your internet traffic is end-to-encrypted, some protocols (e.g., DNS) is natively transmitted “in-clear”. Unencrypted protocols can leak considerable information about your device and your activities; not only can this traffic be intercepted and analysed by anyone that shares the same network, this traffic can be manipulated and altered.

Employing a correctly configured VPN ensures that all your traffic that is transmitted on the “untrusted” public networks cannot be monitored or manipulated.